Dd

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dd
Maintainer: Paul Rubin, David MacKenzie, Stuart Kemp
OS: Linux,Windows,Mac OS X
Genre: Disk imaging
License: GPL
Website: ftp.gnu.org/gnu/coreutils/

dd, sometimes called GNU dd, is the oldest of the imaging tools currently in use. It is part of the coreutils package. A command line program that has been ported to many operating systems, dd uses a complex series of flags to allow the user to image or write data from and to raw image files.

There are a few forks of dd for forensic purposes including dcfldd, sdd, dd_rescue, ddrescue, dccidd, a Microsoft Windows version that supports reading physical memory.

Example

Here is a common dd command:

UNIX/Linux

dd if=/dev/hda of=mybigfile.img bs=65536 conv=noerror,sync

Windows

dd.exe if=\\.\PhysicalDrive0 of=d:\images\PhysicalDrive0.img --md5sum --verifymd5
--md5out=d:\images\PhysicalDrive0.img.md5

Tips

When using dd, be sure to specify a proper "conversion" that will ignore bad blocks. You can also improve imaging performance by specifying a blocksize that is larger than the default of 512 bytes.

Cautions

Use extreme care when typing the command line for this program. Reversing the if and of flags will cause the computer to erase your evidence!

See also

External Links